Passing the buck again

We are using a TP link AC1200 ER4 as a router and added another one yesterday to enhance our coverage.It worked a bit and now we have no internet.Our ISP is RSA web.We have contacted them yesterday,plugged in a LAN cable to laptop and there’s no internet.All the lights on the black Frogfoot box are on.The IPV4 address is apparently wrong.Now who is responsible for restoring our line?We have security cameras linked to wifi not working.Frogfoot says call ISP,ISP says Frogfoot needs to assist.Internet service is poor in SA.So so sad